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        검색결과 1,231

        701.
        2009.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We investigate the degeneracy in the pattern of central microlensing perturbations of a pair of planetary systems where the planets are located from the primary with projected separations in units of the Einstein radius s and s-1, respectively. From this, we confirm the fact that although alike, the patterns of central perturbations induced by a close (s < 1) planet and a wide (s > 1) planet are not identical and the degree of difference depends on the planet/primary mass ratio and the planet-primary separation. We find that the difference can be greater than 5% for planetary systems with lensing parameters located in the parameter space of (1/1.8 < lsl < 1.8, q > 5 x 10-3), (1/1.3 < lsl < 1/3, q > 1 x 10-3), and (1/1.2 < lsl < 1.2, q > 5 x 10-4), where q represents the planet/primary mass ratio. Although this range occupies a small fraction of the entire parameter space of planetary systems, we predict that the chance of resolving the close/wide degeneracy would not be meager considering that the planet detection efficiency is higher for planets with resonant separations (s ~ 1) and heavier masses. We also find that the differences between the perturbation patterns are basically caused by the effect of the planetary caustic. This explains the tendency of the perturbation difference where (1) the difference increases as the planet/primary mass ratio increases and the separation approaches the Einstein radius, (2) the region of major difference is confined within the region around the line connecting the central and the planetary caustics, and (3) a wide (close) planetary system has a more extended central perturbation region toward the (opposite) direction of the planet.
        4,000원
        702.
        2009.06 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        We propose a diagnostic that can resolve the planet/binary degeneracy of central perturbations in caustic-crossing high-magnification microlensing events. The diagnostic is based on the difference in the morphology of perturbation inside the central caustics induced by a planet and a wide-separation binary companion. We find that the contours of excess exhibit a concentric circular pattern around the caustic center for the binary-lensing case, while the contours are elongated or off-centered for the planetary case. This difference results in the distinctive features of the individual lens populations in the residual of the trough region between the two peaks of the caustic crossings, where the shape of the residual is symmetric for binary lensing while it tends to be asymmetric for planetary lensing. We determine the ranges of the planetary parameters for which the proposed diagnostic can be used. The diagnostic is complementary to previously proposed diagnostics in the sense that it is applicable to caustic-crossing events with small finite-source effect.
        4,000원
        704.
        2009.05 구독 인증기관·개인회원 무료
        Males of many cricket species produce calling songs to attract receptive, conspecific females. Calling songs which affected by calling pattern are critical for male mating success, since male with no or limited calling songs are unable to attract female crickets. Investigating among- and within-individual variation in calling pattern may reveal the presence of alternative mating tactics such as attracting females by producing calling songs or being satellites in which males intercept females who are attracted to calling males. In this study, I investigated patterns of calling song production during the entire adulthood of 32 laboratory-reared and 24 field-captured individuals of Teleogryllu emma. Using recording system which can record acoustic signals from up to 32 individuals simultaneously, I measured daily calling output (DCO) and total calling output (TCO) in addition to acoustic parameters of calling songs and classified T.emma males into consistent and inconsistent singers based on the consistency of singing. Consistent singers lived longer, sang longer both in a day and during the lifetime than the inconsistent singers. These results suggest that the consistent singers in this study may be considered to employ the calling tactic. In lab-reared individuals, there seemed to be a trade-off between increasing pulse duration and length of phrases and ling chirp although older males produced calling songs with longer ling chirps and more multiple phrases.
        705.
        2009.05 구독 인증기관·개인회원 무료
        Ascotis selenaria, one of the major Geometridae moths, annually damages the citrus leaves and fruits. This study was focused to identify the sex pheromone components of A. selenaria in order to monitoring and control its population. Adult female and male were usually emerged at the time between 2 hour before and 2 hour afterlights-off in 16L:8D photoperiod. Mating, irrespective in female age, started at 2 hour after lights-off and peaked between 4 hour and 6 hour after lights-off. They copulated for 3 hour 47 min per pair. Gland extract of virgin female was analyzed with GC-MS and GC-EAD.Z,Z-6,9-3,4 epoxy nonadecadiene (Z,Z-6,9-3,4 epo- 19Hy) was identified as the candidate. Both of stereo isomer, Z,Z-6,9-3R,4S epo- 19Hy and Z,Z-6,9-3S,4R epo- 19Hy, showed a strong EAG response in male antennae. Further study like field attraction test should be needed to clarify the sex pheromone composition and in A. selenaria. Age and time were related with the amount of sex pheromone components biosynthesized in A. selenaria gland. 0 day old female had 112.7ng per gland at 5 hour after lights off and the amount was decreased as they aged. The sex pheromone biosynthesis started from lights-off and showed the increasing tendency during scotophase.
        706.
        2009.05 구독 인증기관·개인회원 무료
        The soybean aphid, Aphis glycines Matsumura 1917, is well known as a soybean pest in the world. Recently, it has been introduced to North America causing serious damage in U.S. As a cooperative research with USDA-ARS, we have investigated A. glycines in soybean fields, and also examined the colonies on the overwintering host Rhamnus davurica in order to find its natural enemies. It was generally reported that A. glycines has host alternation between the soybean, Glycine max (summer host) and the Dahurian buckthorn, Rhamnus davurica (winter host) in East Asia. However, it was very difficult to identify the soybean aphid, A. glycines, from R. davurica due to the co-existance of at least three Aphis species and the seasonal polymorphisms of each species (e.g, gynopara, ovipara, and male). For species identification, we tested 3 molecular markers, mitochondrial COI, COII, and nuclear EF1α, for 14 collected samples (7 samples from G. max and 7 samples from R. davurica). As a result, we found two different species, A. gossypii and other Aphis sp., are mixed together with A. glycines on R. davurica. We report the biology of A. glycines in Korea, and present species identification using molecular phylogenetic approach.
        711.
        2009.03 구독 인증기관 무료, 개인회원 유료
        Thrombin-induced platelet microbicidal protein (tPMP) is a small cationic peptide that exerts potent in vitro microbicidal activity against a broad spectrum of human pathogens, including Staphylococcus aureus and Streptococcus rattus BHT. Earlier evidence has suggested that tPMP targets and disrupts the bacterial membrane. However, it is not yet clear whether membrane disruption itself is sufficient to kill the bacteria or whether subsequent, presumably intracellular, events are also involved in this process. In this study, we investigated the microbicidal activity of rabbit tPMP toward S. rattus BHT cells in the presence or absence of a pretreatment with antibiotics that differ in their mechanisms of action. The streptocidal effects of tPMP on control cells (no antibiotic pretreatment) were rapid and concentration-dependent. Pretreatment of S. rattus BHT cells with either penicillin or amoxicillin (inhibitors of bacterial cell wall synthesis) significantly enhanced the anti-S. rattus BHT effects of tPMP compared with the effects against the respective control cells over most tPMP concentration ranges tested. On the other hand, pretreatment of S. rattus BHT cells with tetracycline or doxycycline (30S ribosomal subunit inhibitors) significantly decreased the streptocidal effects of tPMP over a wide peptide concentration range. Furthermore, pretreatment with rifampin (an inhibitor of DNA-dependent RNA polymerase) essentially blocked the killing of S. rattus BHT by tPMP at most concentrations compared with the respective control cells. These results suggest that tPMP exerts anti-S. rattus BHT activity through mechanisms involving both the cell membrane and intracellular targets.
        4,000원
        712.
        2009.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Transcriptomic changes in the brain of Limanda yokohamae were investigated to understand the environmental condition of Masan Bay, Korea. Differentially expressed genes (DEGs) in the brain of the flat fish from Masan Bay were identified by comparing those
        4,000원
        713.
        2008.12 구독 인증기관 무료, 개인회원 유료
        Gingival overgrowth can cause dental occlusion and seriously interfere with mastication, speech, and dental hygiene. It is observed in 25 to 81% of renal transplant patients treated with cyclosporine A (CsA). CsA-induced gingival overgrowth (CIGO) is caused by quantitative alteration of the extracellular matrix components, particularly collagen. However, the molecular mechanisms involved in the pathogenesis of CIGO remain poorly understood, despite intense clinical and laboratory investigations. The aim of the present work is to identify differentially expressed genes closely associated with CIGO. Human gingival fibroblasts were isolated by primary explant culture of gingival tissues from five healthy subjects (HGFs) and two patients with the CIGO (CIGO-HGFs). The proliferative activity of CsA-treated HGFs and CIGO-HGFs was examined using the MTT assay. The identification of differentially expressed genes in CsA-treated CIGO-HGF was performed by differential display reverse transcriptase-polymerase chain reaction (RT-PCR) followed by DNA sequencing. CsA significantly increased the proliferation of two HGFs and two CIGO-HGFs, whereas three HGFs were not affected. Seven genes, including the beta subunit of prolyl 4-hydroxylase (P4HB) and testican 1, were upregulated by CsA in a highly proliferative CIGO-HGF. The increased P4HB and testican-1 mRNA levels were confirmed in CsA-treated CIGO-HGFs by semiquantitative RT-PCR. Furthermore, CsA increased type I collagen mRNA levels and suppressed MMP-2 mRNA levels, which are regulated by P4HB and testican-1, respectively. These results suggest that CsA may induce gingival overgrowth through the upregulation of P4HB and testican-1, resulting in the accumulation of extracellular matrix components.
        4,000원
        714.
        2008.12 구독 인증기관 무료, 개인회원 유료
        It has been reported that the antimicrobial susceptibility patterns of viridans streptococci vary according to geographical region. Although several studies on the antibiotic resistance of viridans streptococci in foreign countries have been reported, little is known about the distribution of resistance among viridans streptococci in Korea. In this study, 88 isolates of viridans streptococci from Korean students' dental plaque were identified as 12 different species. The susceptibility of these isolates to 8 antibiotics was investigated. The in vitro antibiotic activity of penicillin G, ampicillin, vancomycin, streptomycin, gentamicin, erythromycin, amoxicillin, and tetracycline was measured by the broth microdilution method. The range of the minimum inhibitory concentrations (MIC), MIC50, MIC90, and the percentage of the susceptible isolates were determined. Streptococcus mutans and Streptococcus salivarius were susceptible to the 8 antibiotics. Isolates with resistance to vancomycin, streptomycin, and amoxicillin were not found. The overall resistance rates of the 88 isolates to penicillin G, ampicillin, gentamicin, erythromycin, and tetracycline were 12.5%, 62.5%, 62.5%, 26.1%, and 26.1%, respectively.
        4,000원
        715.
        2008.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Recently, Choe & Cheng (2002) have demonstrated that multiple magnetic flux systems with closed configurations can have more magnetic energy than the corresponding open magnetic fields. In relation to this issue, we have addressed two questions: (1) how much fraction of eruptive solar active regions shows multiple flux system features, and (2) what winding angle could be an eruption threshold. For this investigation, we have taken a sample of 105 front-side halo CMEs, which occurred from 1996 to 2001, and whose source regions were located near the disk center, for which magnetic polarities in SOHO/MDI magnetograms are clearly discernible. Examining their soft X-ray images taken by Yohkoh SXT in pre-eruption stages, we have classified these events into two groups: multiple flux system events and single flux system events. It is found that 74% (78/105) of the sample events show multiple flux system features. Comparing the field configuration of an active region with a numerical model, we have also found that the winding angle of the eruptive flux system is slightly above 1.5π.
        4,000원
        716.
        2008.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The purpose of this study was to establish the reliability of the Trunk Impairment Scale (TIS) translated into Korea in patients with stroke. It also aims to score the quality of trunk movement and to be a tool for the treatment. The TIS consists of three subscales that static sitting balance, dynamic sitting balance and co-ordination. The TIS score ranges from a minimum of 0 to a maximum of 23. Twenty-five stroke patients (13 males, 12 females) were examined by two physiotherapists. Interrater and test-retest reliability were assessed. Kappa and weighted kappa values for the items of the trunk assessment of the TIS ranged from .67 to 1.00. Intraclass correlation coefficients for interrater and test-retest agreement were .95 and .97. Cronbach alpha coefficients for internal consistency range from .87 to .97. The TIS provide reliable assessments for the trunk and are valid scales for measuring trunk performance in patients with stroke. TIS can be used as a guideline for treatment and the assessment of quality of trunk activity.
        4,000원
        717.
        2008.11 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cross-legged sitting postures are commonly assumed during computer work. The purpose of this study was to determine the effects of leg crossing on trunk muscle activity while typing at a computer. Trunk muscle activity was measured in three 8 different sitting postures, in random order. These posture were: normal sitting with a straight trunk and both feet on the floor (NS), upper leg crossing (ULC), and ankle on knee (AOK). The right leg was crossed onto the left leg in both cross-legged postures. Twenty able-bodied male volunteers participated in this study. Subjects typed on a computer keyboard for one minute. Surface electromyography (EMG) was used to record bilateral muscle activity in the external oblique (EO). internal oblique (IO), and rectus abdominis (RA). The EMG activity of each muscle in the NS posture was used as a reference (100% EMG activity) in relation to the two cross-legged postures. Muscle activity in the right EO. right IO, and left IO was significantly lower in the ULC posture than in the NS posture. In contrast, muscle activity in the right RA was significantly higher in the ULC posture than in the NS posture. Muscle activity in the tight RA was significantly higher in the AOK posture, as compared to the NS posture, whereas activity in the left IO was significantly lower in the AOK posture, as compared to the NS posture. The right-left muscle activity ratios in the EO and IO showed significantly different patterns in the cross-legged postures, suggesting that asymmetrical right-left oblique muscle activity had occurred.
        4,000원